Hydrocarbon oil conversion process by catalysis and hydrogen donor diluent non-catalytic cracking



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Herbert G. M. Fischer Inventor y Q 4 004) Ahorney United States Patent2,772,213 HYDROCARBON OIL CONVERSION PROCESS BY CATALYSIS AND HYDROGENDONOR DILUENT NON-CATALYTIC CRACKING Herbert G. M. Fischer, Westfield,N. J., assignor to Esso Research and Engineering Company, a corporationof Delaware Application June 11, 1954, Serial No. 435,993

' 5 Claims. (Cl. 19649) The present invention relates generally to theconversion of hydrocarbon oils. It pertains particularly to a processand a system for converting heavy petroleum oils to lighter and morevaluable products by catalysis and hydrogen donor diluent cracking.

Recently a process termed hydrogen donor diluent cracking (HDDC) hasbeen proposed. In this process, heavy oil is upgraded by admixing itwith a hydrogen donor diluent material that contains aromatic-naphthenicconstituents, and thermally cracking the mixture. The donor diluent is amaterial such as a thermal tar boiling in the range of, preferably, 650to 1000 F. having the ability to take up hydrogen in a hydrogenationzone and readily release it in the thermal cracking zone. The donormaterial is partially hydrogenated by conventional methods using,preferably, a sulfur insensitive catalyst like molybdenum sulfide. Inthis manner of hydrocracking of oils, the oil being upgraded is notcontacted directly with the catalyst and does not, therefore, impair itsactivity by contamination. The amount of concomitant light gases andcoke produced by this process is relatively small, usually being in theorder of about 5 to This technique of HDDC is more fully depicted incopending application, entitled, Upgrading of Heavy Hydrocarbon Oils, byLanger et al., S. N. 365,335, filed on July 1, 1953.

The present invention, by application of the above method of hydrogendonor diluent cracking to heavy, low value hydrocarbons such as vacuumresidua, tars, asphalts, etc., and by selection of a catalytic cyclestock as a source of hydrogen donor diluent, proposes an attractivecombination process heretofore unappreciated. By use of a normallysurplusage catalytic cycle stock as the donor diluent and by specificprocessing sequences, the HDDC process is advantageously integrated withcatalytic cracking processes to yield a highly eflicient petroleum oilconversion process.

it is, accordingly, a major object of the present invention to converthydrocarbon oils, particularly heavy petroleum oils boiling above about1000 F., to lighter, more valuable compounds. Another object is todevelop a method for processing petroleum oils typified by a minimumproduction of degradation products, e. g., light gases and coke. Aspecific object is to propound a proces for upgrading hydrocarbon oilshaving as essential features the steps of catalytic cracking andhydrogen donor diluent cracking of selected fractions of the oils.Further objects and advantages will appear more clearly as the attacheddrawing, depicting schematically a preferred embodiment of the inventionand forming a part of this specification, is discussed in detail.

The attached drawing illustrates diagrammatically a preferred processadapted to achieve the objects of this invention.

Generally the objects of this invention are obtained by catalyticallycracking selected gas oils to obtain products of high quality and heavycycle stocks and partially hydrogenating a portion or all of the heavycycle stocks. The hydrogenated cycle stock is then blended with ahydrogen deficient material such as a vacuum residuum andthe resultingmixture is thermally treated or cracked to obtain naphthas and light andheavy thermal gas oils.

" 2,772,213 Ce Patented Nov. 27, 1956 cause not all of the hydrogenintroduced into the cycle stock is transferred, the cycle stock isupgraded by the residual hydrogen remaining after the HDDC treatment,and is an improved catalytic cracking feed stock.

This invention proposes a processing sequence in which a suitablefraction of catalytic cycle stock, preferably a fraction boiling in therange of 650 to 1000 F., is hydrogenated for use as a donor diluentduring thermal cracking of petroleum residua. For optimum operation, asmuch hydrogen as possible is introduced into the diluent short ofreducing its activity by complete hydrogenation of the polynucleararomatics to naphthenes. This diluent is blended with residuum using ashigh a diluent concentration as possible consistent with the relativevolumes of cycle stock and residuum available. After thermal cracking ortreatment, the recovered diluent fraction, e. g., material boiling aboveabout 650 F., is returned to catalytic cracking as an improved cyclestock rather than regenerated and returned to the donor diluent crackingstage as is customary in normal HDDC operations.

As is known by the art, as the aromatic to naphthene ratio of acatalytic feed stock increases, cracking quality decreases. In thepresent invention, the residual hydrogen remaining in the cycle stockafter HDDC serves to improve the quality of the cycle stock as acatalytic cracking charging stock by substantially decreasing itsaromatic to naphthenic ratio.

Although the present invention is applicable to any type of crude oil,distillate or residual fractions therefrom, or mixtures thereof, it ismost advantageously applied to the processing and converting of crudesthat normally yield high percentages of residual fractions. As will beseen, in the practice of this invention, each fraction of an oil isselectively processed under conditions designed to secure optimum yieldsof motor gasolines and of middle distillates suitable for fuels for homeor industrial heating, for use in diesel engines or gas turbines, etc.

For convenience, the pertinent operating conditions applicable to thefollowing example are summarized in Table I. Referring now to thedrawing, a crude enters the process by line 1, is heated in furnace 2 toa suitable temperature, and transferred to an atmospheric fractionationcolumn 4 by line 3. Light gases are removed from the column overhead byline 5, a naphtha fraction and a heating oil fraction are removed bylines 6 and 7 respectively. Line 8 removes a gas oil fraction, boilingin the range of about 650 to 900 F. and designated as feed for catalyticcracking. The naphtha, heating oil and gas oil fractions can, of course,be further processed by conventional methods such as hydrofining,stabilization, blending, etc., to obtain commercially salable products.

Advantageously, the heavy portion of the naphtha can be subjected toprocesses such as hydroforming to increase the quality and octane ratingof the gasoline product and to, concurrently, produce hydrogen. Thishydrogen can then be used to hydrogenate the diluent, as is hereinafterdescribed. With proper selection of operating conditions and feedstocks, the process, including the hydroforming step, may be made to besubstantially balanced as to hydrogen production and consumption. If acrude source does not, however, supply a sufii-cient amount of hydrogen,then extraneous hydrogen is used.

Line 10 removes the residuum from the fractionation 3. tower andtransfers it to a furnace 11 wherein it is reheated to a suitabletemperature for further separation. From the furnace, the residuum istransferred by line 12 to a vacuum distillation unit 13. Further gasoils are removed from the residuum by the vacuum distillation and areblended with the material in lines by line 14. Heavy vacuum residuumboiling above about 1000 F. is removed from the vacuum tower by line 15.It is to be appreciated that in certain applications, there will be noneed or justification for a vacuum distillation unit. In such a case,the atmospheric bottoms can be transferred to the HDDC unit.

The gas oil in line 8 is mixedv with thermal gas oil, obtained ashereinafter described, in line 16 and passed to a catalytic crackingunit 17. If desired, other catalytic cracking feed stocks may beadmitted to the process by line 18. Suitable tankage may be interposedat this point to collect and blend these various feed streams to thecatalytic cracking unit to add operating stability to the process.

Any conventional catalytic process is suitable for the purpose of thisinvention. Such a catalytic process may have a fluid bed, a fixed bed ora gravitating type of bed. A fluidized catalyst bed reactor with a fluidbed regenerator (not shown) is preferred and is used as thecatalyticprocess in this example. The effluent from the catalyticcracking unit is transferred to a fractionation column 20 by line 19.Lines 21, 22 and 23 remove light gases, naphthas and heating oilsrespectively, from column 20 as products of the process. Line 24 removesa cycle stock boiling in the range of about 650 to 1000 F. anddesignated as feed to a hydrogenation unit 30, In

, some instances it may not be necessary to hydrogenate all the cyclestock to serve as a diluent during HDDC. Thus, lines 25 and 25a may beused to recycle a portion of this cycle stock to the catalytic crackingunit. A portion or all of the excess cycle stock may be removed from theprocess as product by lines 25 and 25b.

Broadly, any material boiling above the gasoline range from thecatalytic cracking unit will serve as a hydrogen donor diluent afterpartial hydrogenation. In certain applications or with particular feedstocks, it may be desired to use as a hydrogen donor diluent fractionsboiling above the preferred diluent boiling range in order to maintainheat and material balances and/or to obtain optimum productdistributions. It is to be understood that although the preferred donordiluent boiling range is from about 650 to 1000 F., other diluentboiling ranges can be satisfactorily used. For example, when heart cutrecycle catalytic cracking is practiced, the diluent boiling range canbe 900 to 1050 F. It shouldbe noted that as the boiling point of aselected diluent increases, its aromaticity will increase and thus itsability to take up and to transfer hydrogen will increase;

Bottoms areremoved from fractionator 20 by line 27; Although it is notshown, a separation step can be incorporated at this point toconcentrate the catalytic solids. remaining in the bottoms, as iscustomary in some processes. ing process Without such a separation step.A portion of' the bottoms, or slurry oil, if a separation step be used,may be recycled to the cracking unit by line 27a. It is desirable toremove by line 27b a portion of the bottoms as purge to prevent anexcessive build-up of contaminants in the system.

Generally, a petroleum oil process can consume roughly about 840% of thematerial processed as fuel to'supply heat. As the process of thisinvention minimizes the amount of degradation and low value productsproduced, this process can be made to be substantially balanced asHowever, it is known to operate a catalytic crack-- tov fuelrequirements. The light gases produced will oils existing beyond thisrequirement can be recycled substantially to extinction.

The material to be hydrogenated is transferred toa hydrogenation unit 30which is supplied by line 31 withhydrogen from a source not shown.Conventional operating conditions are used during the hydrogenation andit is preferred to use a relatively sulfur insensitive catalyst such asmolybdenum sulfide or cobalt molybdate. Line 32 removes tail gases fromthe hydrogenator, a portion of which may be recycled byline 33.

The conditions are so chosen that the diluent is only] partiallyhydrogenated for it has been found that complete hydrogenation greatlyreduces the effectiveness of the donor diluent. The. diluent should pickupenough easily removable hydrogen. to be efiective as a donor, but

not enough to approach saturation or to convert it substantially tonaphthenes. However, the degree ofhydrogenation used in this inventionis generally higher than that normally used inHDDC operations.

The partially hydrogenated donor diluent is transferred via line 34 tothe HDDC unit 38. The hydrogen-deli cient material to be upgraded issupplied tothe'unit by line 35. Thishydrogen deficient material willbe-composed primarily of the vacuum residuum supplied by line 15.However, it maybe desired in some applications to also subject other lowvalue materials to HDDC.

These can be admitted to the process by line 26.-; The

relative proportions of diluent and residuum used will depend. upon thedegree of hydrogenation of the diluent,

the amounts of the materials available and like factors.

The resulting mixture is passed to furnace 36, wherein it is. heated toa; conventional; thermal. cracking temperature, e. g., 750 to 1000" F.under a pressure to main: tain the mixture substantially in the liquidstate. From the furnace, the heated mixture is transferred by line 37 toa soaking or time drum 38, wherein the mixture is held for a. suflicientperiod of time to allow the crack-:; l ing and hydrogen exchange to'take place to the degree desired. In some cases, such as invis-breakingtypeop erations, a soaking drum may not be required.

After the thermal cracking, the cracked mixtureis transferred to afractionation tower 40 by line 39'. Light, V

larly suitable as a charging stock to the catalytic crack: Bottomsboiling above about 1000 F. are reing unit. 7 moved from fractionator 40by line 43, a major portion of which may be recycled for. furthertreatment. It is desirable, however, to purge or bleed oifla portion of.

the contents. :of line 43 by line 44 in order, to prevent excessivebuildup of contaminants in the system and to provide fuel to theprocess.

An attractive alternative processing scheme is to pass the product fromthe HDDC unit directly to fractionator- 4 by lines 39, 45 and 3 to beseparated-therein whereby fractionator 40 is eliminated.

To further elucidate this example, Table I summarizes operatingconditions pertinent to the presentinvention and presents a specificexample of operating conditions.

Example 1 of Table II lists the products obtainable by stock whenconventional processing techniques are used,

c. g., primary fractionation, vacuum distillation, andjcatalyticcracking of the virgin gas oil with heartcut recycle.

By comparison of the two examples-,theadvan'tages ob-' tainable by,practice of the present invention are readily Y apparent. It can be seenthat this invention results in a 95% decrease in the amount of residualoil produced.

TABLE I Range Example Catalytic Cracking Conditions, Fluid Unit:

Catalyst Temperature, T. Pressure, p. s. i. g Feed Rate, WJHn/WCatalyst/oil ratio 430 F. Conversion per pass Vol. percent HydrogenationConditions:

Catalyst Temperature, F Pressure, p. s. i. g Throughput, V./V./hr HzConsumed, S. C. 1?./

bbl. diluent. HDDC Conditions (Coil and] or Drum)- Silica Alumina.

Nickel Tungsten Sulfide. 650.

Diluent/ Oil Ratio 1.2.

Diluent Boiling Range, F 650 to 1,000.

430 F. Conversion per 45.8.

pass, Vol. percent 1 430 F. Conversion is defined as: 100 vol. percentfeed-vol. percent products boiling above 430 F., based on fresh feed.

TABLE II 14. 1 2. 187 7 +10 Flash, F +80 Example Example 1 2 Products,percent based on Feed:

Light Gas, 03-, Wt. percent- At-mospheric fractionator 0. 1 0. 1Catalytic Unit fractionator- 4. 6 3. 7 HDDC Unit iractionator 2.

Total 7. 2 3.8

Naphtha, C4- 430" F., Vol. percent- Vir in 7. 5 7. 5 25. 3 l9. 9 19. 4

Total 52. 2 27. 4

Heating Oil, 430-650 F., Vol. percent ir in l7. 5 l7. 5 Catalytic 11. 28. 8 HDDC 16. 7

Total 45. 4 26. 3 1,000t F.+Bott on1s (Inc. Bleeds), Vol. percenCatalytic (Heavy Cycle Stock) 1. 1 O. 9 HDDC 0. 9 Vacuum 41 Total 2.041. 9

Coke (including catalytic carbon) 8. 5 6. 6

Internal Flows, Vol. percent based on feed:

Gas Oils to Catalytic Unit, 650 to 1,000 F.-

Source: Virgin 34. 5 HDDC Unit 1 50. 9

Total 85. 4

Diluent to Hydrogenator, 650 to 1,000 F 48 Vacuum residuum to HDDC Unit,1,000 F.+ 41

Total 89 1 Includes diluent recycled.

Although the above example depicts the present process as initiatingwith the separation of a. whole crude, the process is not limitedthereby. The catalytic cracking charging stock can originate from anyconvenient source and the hydrogen deficient material upgraded in theHDDC unit can include tars, asphalts, extracts, shale oils, coal tars,pitches, whole crudes, residual and distillate fractions therefrom, ormixtures thereof,

Having described the invention, what is sought to l protected by LettersPatent is succinctly set forth in t1 following claims.

What is claimed is:

l. A process for converting hydrocarbon oils Whi( comprisescatalytically cracking heavy distillate oils 1' a catalytic crackingzone under catalytic cracking co] ditions, separating from the efiluenttherefrom a cyc stock, partially hydrogenating said cycle stock in a hjdrogenation zone under hydrogenation conditions to 01 tain a hydrogendonor diluent, admixing said hydroge donor diluent with a relativelyhigh boiling heavy oi cracking the mixture in a thermal treating zoneund: non-catalytic hydrogen donor diluent cracking cond tions,separating from the thermally treated mixtln thermal gas oils includingspent hydrogen donor diluer and passing said thermal gas oils to saidcatalytic cracl ing zone to form at least a portion of said heavydistilla1 oils.

2. A process for upgrading hydrocarbon oils compri ing catalyticallycracking a petroleum oil :boiling in t1: range of 650 to 1000 F. in acatalytic cracking zon separating the eflluent therefrom into at leastprodu fractions boiling in the naphtha and heating oil range a cyclestock fraction boiling in the range within tl limits of 650 to 1000 F.and bottoms boiling aboi 1000 F., partially hydrogenating at least aportion said cycle stock in a hydrogenation zone, to obtain hydrogendonor diluent, admixing said hydrogen don: diluent with a hydrogendeficient oil boiling above abol 1000 F. in a proportion in the range of0.25 to 2 V0 umes diluent/volume of oil, thermally treating the nsulting mixture at a temperature above 750 F. in non-catalytic thermalcracking zone, separating from tl: efiluent from said thermal crackingzone into furthc product hydrocarbons and a recycle fraction includirspent hydrogen donor diluent boiling in the range 4 about 650 to 1000F., and returning said recycle fra tion to said catalytic cracking zoneto be treated therei along with the said petroleum oil.

3. The process of claim 2 wherein said petroleui oil boiling above about1000 F. comprises a vacuui residuum and a bottoms fraction obtained fromthe e fluent from said thermal cracking zone.

4. A method of processing petroleum oils which con prises separating acrude oil into at least product hydr( carbons, gas oils and residuumboiling above about 1000 F., catalytically cracking at least a portionof said g2 oils along with a thermal cycle stock, obtained as heninaiter described, separating the catalytically cracked 0 into at leastfurther product hydrocarbons, catalytic cycl stock and bottoms,partially hydrogenating at least portion of said catalytic cycle stock,admixing the h drogenated material with said residuum, thermally cracling the resulting mixture at a treating temperature abov 750 F., undernon-catalytic hydrogen donor diluer cracking conditions, separating thethermally cracke mixture into at least a still further producthydrocarbon thermal cycle stock which includes partially dehydn genatedproducts from said hydrogenated material an residue, and recycling andadmixing said thermal cycl stock with said portion of gas oils to becatalyticall cracked therewith.

5. The process of claim 4 when said thermally cracke mixture is admixedwith said crude oil and the resultin mixture is separated in a commonseparation zone.

References Cited in the file of patent UNITED STATES PATENTS 2,426,929Greensfelder Sept. 2, 194 2,459,465 .Smith Jan. 18, 19 2,467,920 Voge eta1. Apr. 19, 19 2,620,293 Blue et al. Dec. 2, 195

1. A PROCESS FOR CONVERTING HYDROCARBON OILS WHICH COMPRISESCATALYTICALLY CRACKING HEAVY DISTILLATE OILS IN A CATALYTIC CRACKINGZONE UNDER CATALYTIC CRACKING CONDITIONS, SEPARATING FROM THE EFFLUENTTHEREFROM A CYCLE STOCK, PARTIALLY HYDROGENATING SAID CYCLE STOCK IN AHYDROGENATION ZONE UNDER HYDROGENATION CONDITIONS TO OBTAIN A HYDROGENDONOR DILUENT ADMIXING SAID HYDROGEN DONOR DILUENT WITH A RELATIVELYHIGH BOILING HEAVY OIL,